PROJECT SUMMARY/ABSTRACT: Among men, prostate cancer is the most common non-skin cancer and second-leading cause of cancer death, with over 220,000 new diagnoses expected in 2015. Approximately 14% of men will be diagnosed with prostate cancer in their lifetime1. Current treatment options for prostate cancer, however, have sub-optimal incidences of side effects that have a significant impact on patients' quality of life, including urinary incontinence and sexual dysfunction. As prostate cancer patients may live with the side effects of their treatment for decades, there is a critical need for lower-toxicity treatment techniques with an equal or greater probability of cancer control than current techniques. Here we propose a new prostate cancer treatment technique, Rotating Shield Brachytherapy (RSBT). RSBT uses a novel radiation source, 153Gd. Unlike the 192Ir radiation source used in existing radiotherapy approaches, 153Gd can be partially shielded, which enables the radiation source to emit a deliberately non-symmetric dose distribution. This effectively directs radiation away from sensitive, healthy tissues and into tumor tissue, and therefore offers several advantages over existing treatment techniques. Our preliminary data indicate RSBT stands to become the prostate cancer treatment with the lowest incidence of resulting sexual dysfunction, gastro-intestinal, and genitourinary toxicity due to its ability to reduce urethral, rectal, and bladder dose relative to conventional treatments. We hypothesize RSBT will further enable prostate cancer dose escalation beyond conventional methods, without increasing dose to healthy tissues, thus improving metastasis-free tumor control at 10+ years post-treatment. RSBT may also reduce the number of treatment sessions patients need compared to current therapies. We have already developed concept models of several sub-components of the prostate RSBT system to prove each component can be successfully constructed for eventual integration into a full RSBT prototype system. Here we will demonstrate feasibility of the RSBT approach and its advantages over existing treatments. We will develop a prototype of the needle/catheter/source capable of delivering RSBT. We will develop RSBT apparatus functionality to enable the control and monitoring of the positioning of single catheter with using a simple moving template design that converts translational template motion to rotational catheter motion. We will develop a multiple-catheter control system by integrate the previously-developed components into a complete RSBT prototype and validate the complete system by dose measurement. Successful completion of these aims will demonstrate the feasibility and commercial potential of the RSBT approach. Ultimately, this work will result in an improved, clinically-available prostate cancer treatment. Our technology stands to significantly reduce treatment-related side effects for patients while providing equal or better cancer control, thus improving patients' cancer outcomes and quality of life. 1http://seer.cancer.gov/statfacts/html/prost.html